US2901179A - Printing press - Google Patents

Description

A. BUTTNER PRINTING PRESS Aug. 25, 1959 2 Sheets-Sheet 1 Filed Oct. 26, 1955 IIIIIIA'IIIIIII4 Aug. 25, 1959 A. BUTTNER I 2,901,179

PRINTING PRESS Filed Oct. 26, 1955 2 Sheets-Sheet 2 g =Z==- a A FIG. 5.

2,901,179 Patented Aug. 25, 1959 2',9d1,=17 PRINTING PRESS Artur Biittner, Heidelberg, Germany, assignor to S clinell pressenfabrik Aktiengesellschaft Heidelberg, Heidelberg, Germany, a corporation of Germany Application October 26, 1955, Serial No. 542,938

Claims priority, application Germany November 2, 1954 2 Claims. (Cl. 239--67) This invention concerns printing presses and is more particularly concerned with the provision in such machines of a device for preventing the smudging of a fresh print or impression.

In recent times in order to prevent smudging of fresh prints, especially during the printing of illustrations, dusting or powdering of the printed sheets has been effected to prevent smearing of the wet ink. In the course of time twodifferent processes have been developed for this purpose, which can be briefly described as wet dusting and dry dusting processes.

In the wet dusting process, a rapidly evaporating liquid containing the most finely divided possible solid particles is sprayed over the printed sheet by means of an apparatus having suitably formed nozzles, whereby the liquid constituents evaporate in the air, so that only the solid particles settle on the printed sheet and form a fine layer on the wet print to protect the. sheet following thereupon from causing smudging. These devices operate with a relatively high air pressure of about 3-4 atmospheres in order to attain apositive evaporation.

In the dry dusting process, a dry powder is blown through ashort distance on to the printed upper side of the sheet. This socalled powder duster, in contrast to the wet dusting process, operates with a substantially lower air pressure of about 0.5 atmosphere.

Both processes have their advantages and disadvantages and are not equally suitable forall printing-operations which are encountered; The choice of dusting process and therewith of the correspondingsprayingapparatus depends upon the type of work for which the machine is primarily intended. Apart from consideration of printing technique, the choice of the dustingprocess and hence ofthe spraying equipment of the machine is also extensively influenced by the technical operating conditions, which are variable. In any case, the choice of the dusting process once made occasions a continuance of this form of dusting, since the two processes diifer considerably with regard to the necessary operating pressure of the air used for the sprayer. This is true particularly for dusting arrangements which are permanently built-in to the machine and are not subsequently placed on the machine by the printer. A simple exchange of the dusting device is not possible in suchcases, but necessitates corresponding alterations to the printing machine and the air compressor. It is therefore frequently disadvantageous to technicalprinting practices to be more automatically establishing the air pressure required to operate the device to 'Which the air is applied. v

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic representation of the air of a printing machine, together with two dusting devices connectable theretd.

Fig. 2 is a front elevation of a change-over device. a Fig. 3 is a cross-section of the valve of the changeover device set at the position for wet dusting, the section being taken on line A-A of Fig. l. I

Fig. 4 is a cross-section of the valve of Fig. 3, taken. on the line BB of Fig. l, and

Fig. 5 is a diagrammatic general side elevation of a printing machine having the two dusting devices built into the structure thereof.

A pump cylinder 1 (Fig. 1) for intermittently supplying compressed air and vacuum in timed relation with the operation of a printing machine is disposed in known way' on the frame 2 of a printing machine and is closed by means of a removable cylinder head 3. A piston 6 is moved backwards and forwards in the cylinder 1 by means of a crank 4 and a connecting rod 5 so that it performs one stroke per cycle of operation of the press. The pump cylinder 1 can be opened by means of a cock 7. The compressed air produced in the pump cylinder 1, when the cock 7 is closed is conveyed by a connecting tube 8 and a flexible tube 9 to a nipple 10 communicating with a radial port 10 (Fig. 4) of a valve chamber 11 having an axial bore 11' into which the part 10 opens. The valve chamber 11 has a further radial port 12 which is diametrically opposite the port 10 and communicates with" a nipple-12 which is connected by a flexible tube 13 to a known type of wet spraying device 14. The spraying' liquid for the device 14 is stored in a container 15.

In a transverse plane spaced axially from the ports 16" and 12", the valve chamber is provided with a radial port 16" (Fig. 3) communicating with a nipple 16 connected by a flexible tube 17 to a powder dusting device 18. The dusting devices 14 and 18 are operable only or less bound to a fixed type of dusting process, either the when compressed air is supplied to them. Diametrically opposite the port 16 there is a further port 19' which is open to the atmosphere through a pressure relief valve 19 consisting of a ball 20, a compression spring 21 and an adjusting screw 22. This valve is so adjusted that on use of the powder dusting device 18, it can blow 01f the air compressed above 0.5 atmospheres gauge pressure, so that the powder device 18' only receives through the flexible tube 17, compressed air not exceeding 0.5 atmospheres gauge pressure.

A cylindrical valve member 23 with a handle 24 serves for changing over the compressed air from the wet dusting device 14 to the powder dusting device 18 or vice versa; The valve member 23 is mounted in the axial bore 11" valve chamber 11 so that it can be rotated through approximately the rotary movement being suitably limited by a stop pin 25 on the valve member 23 in conjunction with stop faces 26 reamed in the valve chamber 11. The two limiting positions correspond to the setting of the compressed air to wet dusting or powder dusting. respectively.

The valve member 23 has" an axial passageway 27, the outer end of which is closedby a plug 28 so that it is airtight. Opposite to the ports 10' and 12 in the plane BB (Fig. 1), the valve member 23" is provided with a transverse passageway 29 passing diametrically through it; by means of which these two opposite valve ports can be connected with one another. Transversely to the diametrical passageway 29 and in the same transverse plane, there is formed a radialpassageway 29b, which is displaced 90 from the passageway 29 and does not pass completely through the valve member but terminates in the axial passageway 27 (see Fig. 4). In a plane AA of the valve member spaced axially from the plane BB there is further formed a corresponding transverse bore 30 passing diametrically through the valve member and displaced 90 relative to the bore 29 (Fig. 3).

The valve chamber 11 is attached in any convenient known manner to the frame of a printing machine 2, for example by screws, as shown in Fig. 5.

On the machine frame 2, opposite to the end of the handle 24 of the rotatable valve member 23, is fixed a plate 31 which indicates which of the dusting devices is connected.

The method of operation of the device is as follows:

When the handle 24 is placed in the wet dusting position, the compressed air flows directly through the passageway 29 to the wet dusting device 14, 1.5, while the branch passageway 29a and the passageway 30 are closed, and in consequence the admission of compressed air to the dry powder dusting device 18 is shut off (Figs. 3 and 4). In this position the wet dusting device operates with the full pressure of the compressed air.

When the handle 24 of the valve member 23 is rotated 90, the passageway 29 is closed and consequently the passage of the compressed air to the wet dusting device 14 is shut off; however, the compressed air reaches the central passageway 27 through the radial passageway 29a and hence passes to the transverse passageway 30, which now connects the axial passageway 27 with the port 16 on the one hand and with the pressure relief valve 19 on the other hand, so that the path of the compressed air and the nipple 16 and the flexible tube 17 to the powder dusting device 18 is opened, while at the same time the compressed air acts on the pressure relief valve 19. The latter is so designed and so adjustable that the excess pressure of the compressed air above the lower pressure required for the operation of the powder device, for ex 7 ample 0.5 atmosphere gauge is relieved and only the remaining residual compressed air is supplied to the dry powder device for the agitation of the powder. Moreover, the pressure of the compressed air supplied to the powder device 18 can be regulated by means of the adjustment screw 22 as occasion demands.

If work is to be carried out without dusting, the compressed air can be relieved directly by opening the cock 7 on the pump cylinder head 3, while the air feed pipes to the wet and dry dusting apparatus can be shut E in known manner by means of valves.

What I claim and desire to secure by Letters Patent is:

1. In a printing press having a frame structure and means for receiving printed sheets discharged consecutively from the press, in combination, a pressure-operated wet dusting device and a pressure-operated dry dusting device mounted on said frame structure in position to dust the printed sheets individually on said receiving means as they are discharged consecutively from the printing press, a source of compressed air for operating both of said devices having means cyclically operable to provide air intermittently at a given pressure and at a proper interval during each operational cycle of the press, an improved shifting unit operable at will to alternatively and individually operatively connect said dusting devices with said source of compressed air and automatically provide said devices with optimum, different air pressures at a proper interval of each press operational cycle without need of adjustment of the given air pressure delivered by the source of air pressure, means providing communication between said unit and the source of air pressure and means providing communication between the unit and the dusting devices, said shifting unit comprising a single selector valve having a rotatable valve member operative to a valve closing position and alternatively positionable in a first operative position for placing the wet dusting device in communication with the source of air pressure to 4 operate it and positionable in a second operative position for separately placing the dry dusting device in communication with the source of air pressure to operate it at a predetermined optimum air pressure corresponding to a reduced pressure below said given air pressure, pressureresponsive means in said shifting unit automatically rendered effective to reduce the air pressure at said unit when the valve member is placed in the second position to control the application of said optimum operating reduced air pressure to the dry dusting device, said valve having passageways for alternatively placing the compressed air source in communication with said devices when said valve member is operated alternatively to said two positions and having a passageway for placing said pressureresponsive means in communication with said air source and a passageway providing communication between the unit and said source when said valve member is in said second operative position, and means connected to said valve member operable at will for operating said valve member to said two operative positions.

2. In a printing press having a frame structure and means for receiving printed sheets discharged consecutively from the press, a pressure-operated wet dusting device and a pressure-operated dry dusting device mounted on said frame structure in position to dust the printed sheets individually on said receiving means as they are discharged consecutively from the printing press, a source of compressed air for operating both of said devices having a reciprocably driven piston to provide air intermittently at a given pressure and a vacuum at proper intervals of each operational cycle of the printing press, an improved shifting unit operable at will to alternatively and individually operatively connect said dusting devices with said source of compressed air and automatically provide said devices with optimum, different air pressures at a proper interval of the press operational cycle without need of adjustment of the given air pressure delivered by the source of air pressure, means providing communi cation between said unit and the source of air pressure and means providing communication between the unit and the dusting devices, said shifting unit comprising a single selector valve having a rotatable valve member operative to a valve closing position and alternatively positionable in a first operative position for placing the wet dusting device in communication with the source of air pressure to operate it and positionable in a second operative position for separately placing the dry dusting device in communication with the source of air pressure to operate it at a predetermined optimum air pressure corresponding to a reduced pressure below said given air pressure, a pressure-operated relief valve in said shifting unit automatically rendered effective to reduce the air pressure at said unit when the valve member is placed in the second position to control the application of said optimum operating reduced air pressure to the dry dusting device, said valve having passageways for alternatively placing the compressed air source in communication with said devices when said valve member is operated alternatively to said two positions and having a passageway for placing said pressure-responsive means in communication with said air source and a passageway providing communication between the unit and said source when said valve member is in said second operative position, and handle means connected to said valve member operable at will for operating said valve member to said two operative positions.

References Cited in the file of this patent UNITED STATES PATENTS 1,384,645 Sullivan July 12, 1921 2,014,997 Auger Sept. 17, 1935 2,398,503 Paasche Apr. 16, 1946 2,436,680 Straussler Feb. 24, 1948 2,605,138 Paasche July 29, 1952

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